Recent medical studies suggest that it may be beneficial to deliver therapeutic aerosols or liquid or gas stream to anatomical surfaces within the surgical field of patients that are undergoing open or minimally invasive surgical procedures. In the case of minimally invasive surgery (MIS), the surgical field may be a natural or artificially created body cavity or lumen. Similarly, it may be desirable to deliver therapeutic aerosols to an open anatomical surface. The aerosol formulations may be delivered before a surgical procedure, after a surgical procedure, or in the absence of an adjunctive surgical procedure.
Among problems that physicians have encountered during diagnostic or surgical procedures, using both “open” techniques, and minimally invasive surgical techniques (e.g. laparoscopic), are numerous post procedural complications. These complications can consist of, but are not limited to, post operative pain, infections, tissue adhesions, and tumor formation. Numerous products, such as medications and associated delivery systems, addressing these issues exist on the market to improve the surgical or invasive experience and patient outcomes. Among these products are suction and irrigation wands that are used for flushing tissue sites with sterile water or saline and removing blood. There are medications, which are spread over exposed organs, to coat or provide a barrier between tissue and organs for prevention of adhesions. These materials may be in gel form, sheet form, spray (liquid) form, or aerosol form to coat organs or tissues, or to provide thin layer deposition to the organs in the operative site. Some of these materials may be used in both open and minimally invasive surgical techniques.
A problem with delivering substances to anatomical surfaces in a body cavity is the inability to easily and effectively control delivery to all or a portion of the surgical field. Among the difficulties associated with spraying of liquids, is the pooling and lack of containment of the fluids used with irrigation and aspiration wands. It is also difficult to cover large areas (greater than several square centimeters), and to do so without using much more medicament than is necessary. This contributes to the cost of excessive medication, and adding to the cost and time of the surgery.
In some circumstances it may be desirable to direct aerosol to certain areas within a cavity, particularly the tissue surrounding the entry ports created in a patient's abdomen in order to insert a surgical instrument. The nozzles on many current devices are fixed in orientation with respect to the instrument shaft. As a result, the caregiver must manipulate the shaft to direct the aerosol. This is problematic if the aerosol needs to be directed backward towards the entry point of the shaft, since the end of the shaft is outside the patient, and would need to be positioned in the cavity in order to direct the aerosol towards the inside of the entry port. It may also be problematic during open surgery in circumstances where the spray needs to be directed towards a target site that faces away from the surgical opening, or that is obstructed by an anatomical structure or instrumentation. Although some devices are capable of generating radial aerosol patterns, none are capable of directing an aerosol directly backwards towards the devices point of entry into a surgical cavity.
While some devices have a deflectable tip that allows the user to aim the aerosol, they rely on designs that require a mechanical linkage to bend a hinged tip. These are likely expensive to manufacture due to the mechanical complexity involved.
The spray particles produced by current delivery devices are often quite large and have a high exit velocity from the nozzle. As a result, they have a high inertia due to their relatively large mass and the speed with which they exit the aerosol generation nozzle. The particles tend to travel in a straight line and immediately impact upon the surface in front of them, creating an inertial deposition pattern. In addition, aerodynamic factors cause these larger particles to fall more rapidly than a smaller aerosol. This creates a gravity dependent deposition pattern which preferentially coats the lower surfaces of the cavity. This is problematic when a uniform, even deposition of aerosol is required on the top, bottom, and sides of the surgical cavity. Finally, the large and rapidly moving particles may cause trauma if the nozzle is positioned too close to sensitive tissue.
During a minimally invasive surgical procedure within a body cavity or lumen it may not be possible or convenient to visually determine the location and direction of the aerosol generation nozzle. As a result it may be difficult to determine which part of the cavity the aerosol is directed at. It may also be difficult to systematically manipulate the aerosol nozzle in a pattern that creates a uniform deposition of aerosol on all cavity surfaces.